sledge: English has two words sledge. The sledge [OE] of sledgehammer [15] was once a word in its own right, meaning ‘heavy hammer’. It goes back to the prehistoric Germanic base *slakh- ‘hit’, source also of English slaughter, slay, etc. Sledge ‘snow vehicle’ [17] was borrowed from Middle Dutch sleedse. Like Dutch slee (source of English sleigh [18]) and Middle Low German sledde (source of English sled [14]), its ultimate ancestor was the prehistoric Germanic base *slid- ‘slide’ (source of English slide). Sledging ‘unsettling a batsman with taunts’ [20], which originated in Australia in the 1970s, may have been derived from sledgehammer. => slaughter, slay, sly; sled, sleigh, slide
sledge (n.1)
"heavy hammer," Old English slecg "hammer, mallet," from Proto-Germanic *slagjo- (cognates: Old Norse sleggja, Middle Swedish sleggia "sledgehammer"), related to slege "beating, blow, stroke" and slean "to strike" (see slay (v.)). Sledgehammer is pleonastic.
sledge (n.2)
"sleigh," 1610s, from dialectal Dutch sleedse, variant of slede (see sled (n.)); said by OED to be perhaps of Frisian origin.